Expression of mGluR5 in Pediatric Hodgkin and Non-Hodgkin lymphoma-A Comparative Analysis of Immunohistochemical and Clinical Findings Regarding the Association between Tumor and Paraneoplastic Neurological Disease.

Autoantibodies targeting the neuronal antigen metabotropic glutamate receptor 5 (mGluR5) have been identified in patients with Ophelia syndrome, which describes a co-occurrence of paraneoplastic limbic encephalitis and Hodgkin lymphoma (HL). Little data exist regarding frequency and function of mGluR5 in HL and its potential role in causing seropositive paraneoplastic disease. We studied a representative cohort of pediatric HL and NHL patients (n = 57) using immunohistochemistry and fluorescence staining to investigate mGluR5 expression. All lymphoma tissues displayed positive mGluR5 staining, with focus on Hodgkin-Reed-Sternberg (H-RS) cells. We did not detect any mGluR5 staining in tumor-free lymph nodes, which is consistent with the absence of GRM5 transcripts in RNA-sequencing data from non-malignant B and T cells. The frequent presence in pediatric lymphoma falls in line with reports of mGluR5 expression and associated tumor progression in other malignancies. We tested for correlation with clinical features, focusing on disease progression and neurological symptoms. Low mGluR5 expression in H-RS cells correlated with young patient age (<15 years) and positive histology for EBV infection. Paraneoplastic or neurological symptoms were found exclusively in HL patients. While an impact of mGluR5 on HL severity remains possible, a prognostic value of mGluR5 expression levels requires further investigation.

Biallelic NDC1 variants that interfere with ALADIN binding are associated with neuropathy and triple A-like syndrome.

Nuclear pore complexes (NPCs) regulate nucleocytoplasmic transport and are anchored in the nuclear envelope by the transmembrane nucleoporin NDC1. NDC1 is essential for post-mitotic NPC assembly and the recruitment of ALADIN to the nuclear envelope. While no human disorder has been associated to one of the three transmembrane nucleoporins, biallelic variants in AAAS, encoding ALADIN, cause triple A syndrome (Allgrove syndrome). Triple A syndrome, characterized by alacrima, achalasia, and adrenal insufficiency, often includes progressive demyelinating polyneuropathy and other neurological complaints. In this report, diagnostic exome and/or RNA sequencing was performed in seven individuals from four unrelated consanguineous families with AAAS-negative triple A syndrome. Molecular and clinical studies followed to elucidate the pathogenic mechanism. The affected individuals presented with intellectual disability, motor impairment, severe demyelinating with secondary axonal polyneuropathy, alacrima, and achalasia. None of the affected individuals has adrenal insufficiency. All individuals presented with biallelic NDC1 in-frame deletions or missense variants that affect amino acids and protein domains required for ALADIN binding. No other significant variants associated with the phenotypic features were reported. Skin fibroblasts derived from affected individuals show decreased recruitment of ALADIN to the NE and decreased post-mitotic NPC insertion, confirming pathogenicity of the variants. Taken together, our results implicate biallelic NDC1 variants in the pathogenesis of polyneuropathy and a triple A-like disorder without adrenal insufficiency, by interfering with physiological NDC1 functions, including the recruitment of ALADIN to the NPC.

Public data sources for regulatory genomic features.

High-throughput technologies have led to a continuously growing amount of information about regulatory features in the genome. A wealth of data generated by large international research consortia is available from online databases. Disease-driven studies provide details on specific DNA elements or epigenetic modifications regulating gene expression in specific cellular and developmental contexts, but these results are usually only published in scientific articles. All this information can be helpful in interpreting variants in the regulatory genome. This review describes a selection of high-profile data sources providing information on the non-coding genome, as well as pitfalls and techniques to search and capture information from the literature.

What can go wrong in the non-coding genome and how to interpret whole genome sequencing data.

Whole exome sequencing discovers causative mutations in less than 50 % of rare disease patients, suggesting the presence of additional mutations in the non-coding genome. So far, non-coding mutations have been identified in less than 0.2 % of individuals with genetic diseases listed in the ClinVar database and exhibit highly diverse molecular mechanisms. In contrast to our capability to sequence the whole genome, our ability to discover and functionally confirm such non-coding mutations is lagging behind severely. We discuss the problems and present examples of confirmed mutations in deep intronic sequences, non-coding triplet repeats, enhancers, and larger structural variants and highlight their proposed disease mechanisms. Finally, we discuss the type of data that would be required to establish non-coding mutation detection in routine diagnostics.